“For me to actually be here now looking for a place to live ... it’s really starting to sink in now that it’s become real. I’m no longer a Boston Celtic.”

He was joined on the Brooklyn dais by Garnett and fellow former Celtic Jason Terry, all of whom were dealt to the Nets last week in a blockbuster trade that signaled the dawning of Boston’s new rebuilding era.

Garnett, 37, is joining his third team after spending his first 12 seasons in Minnesota and then six more in Boston. For Terry, 35, who spent just one season in Boston, Brooklyn is his fourth team.

Garnett greeted the Barclays Center news conference by yelling “What’s up Brooklyn,” but also said he took his time contemplating before deciding to sign off on the deal to the Celtics’ Atlantic Division rival.

“Having [Terry] and having Paul with me was a really, really, really big issue,” Garnett said. “I don’t know anyone who loves change, but change has to happen.”

Garnett said the good “bones” of the Nets organization helped him approve the deal. Likewise, Pierce said he that if he had to leave Boston, he’s glad it’s for a place where he can contend for another NBA title.

“The talent is there for a championship team,” he said.

The change in uniforms is stark for Pierce, whose voice cracked at times during the news conference. His number 34 is almost certain to be retired by the Celtics after a long run in which he became the franchise’s all-time second-leading scorer.

And the longtime Celtics captain (who thanked Boston on Tuesday with a series of photos of his favorite memories with the Celtics that he released on his Instagram page) said he sensed his time with the franchise was winding down as Doc Rivers’ slow exit from the team played out earlier this summer.

“You sort of felt it coming. The writing was on the wall,” he said. And while he “mentally prepared” himself for the split, Pierce said it was “difficult” to drop his affiliation with the Celtics.

“It’s business,” he said. “At some point we have to move on. I’m here to create some kind of legacy here in Brooklyn.”

Pierce said he holds no ill will toward the Celtics.

“I would have loved to end my career in Boston,” he said, lamenting that the inability of players to remain in one city for their entire career. “But that day and age is probably over with.”

The Celtics they left behind will be much different next year as new coach Brad Stevens begins a rebuilding era. And Pierce, Garnett and Terry will have to travel back to Boston multiple times to face their old teammates.

The trio now joins a team that is at a similar level to the Celtics of last season. Their addition adds what general manager Billy King called “a championship pedigree” to a roster that already had talented players in Deron Williams, Brook Lopez, and Joe Johnson.

But even Pierce and Garnett acknowledged that they should merely be considered contenders, not front-runners in the Eastern Conference like Miami and Indiana. How quickly they can get on the same page, learn each others’ tendencies, and jell will determine if the Nets can re-create some of the Celtics’ old magic.

But at 37 and 35, respectively, Garnett and Pierce saw this move to Brooklyn as their best chance to add to that championship pedigree, even if it meant severing their ties to the Celtics.